Category: Neonatology

Case: Last week we talked about Jane, an otherwise healthy 2-week old girl. Let’s change the story a bit to hit on another consideration in infants. Instead of simply being febrile and fussy, let’s say that she comes back to the ED, this time afebrile, but lethargic with poor cap refill. How does our differential change now?

Image Credit: Pixabay

What are the important diagnostic considerations for neonates and infants who present very ill?

Infection

Metabolic/Endocrinologic

Trauma

Cardiac

Surgical emergencies

For those of you who like acronyms, consider “THE MISFITS” in neonates and young children presenting with undifferentiated shock (adapted from post on PEM Playbook)

Trauma

Heart Disease/Hypovolemia

Endocrine Emergencies

Metabolic

Inborn errors of metabolism (to get this acronym to work, there may be some repetition)

Seizures

Formula problems (think too little or too much water)

Intestinal disasters

Toxins

Sepsis (while this is last, all very sick infants/children should be evaluated/treated for sepsis)

Today we will focus on the emergency management of inborn errors of metabolism (IEM), specifically at the immediate recognition and management.

Epidemiology and Etiology

IEMs are Individually rare, but more common in aggregate- 1/5000 live births for any IEM (Ewing, 2009)

Remember, “As the neonate has an apparently limited repertoire of responses to severe overwhelming illness, the predominant clinical signs and symptoms can be nonspecific like poor feeding, lethargy, failure to thrive, etc.” (Saudabray, 2002)

Case: Jane is a 2 week-old, previously healthy, ex- full term girl who presents to the ED from her PCPs office after being found to have a temperature of 102.5 rectally. On exam, she is fussy butconsolable and has an otherwise normal exam. In addition to blood and urine studies, you plan to perform a lumbar puncture. What would be other indications and even contraindications for an LP? What are the various techniques? Should you use local anesthesia?

Lumbar Puncture: The basics

Indications

The most common indication for lumbar puncture is to diagnose meningitis (Bonadio, 2014)

Contraindications

Basics of setup

After discussing the case with the team, you decide that Jane has no contraindications and that it is important to rule out meningitis. What do you need, and how do you set up?

1. Equipment

Most (if not all) of your equipment will be included in a commercially available tray (Figure 1 as an example).

In general, you will need the following

Spinal needle (1.5″ or 3″ depending on the patient)

sterile gloves and drapes

Povidone-Iodine scrub

Monometer tune (to measure CSF pressure)

Sterile tubes for CSF collection

Figure 1: LP Tray (Picture from Bonadio, 2014)

2. Position

In the younger child, and in those you need to measure CSF pressures, the child should be placed in the lateral decubitus position

In older children, the seated position can also be used (Figure 2)

Remember, the spinal cord ends around L2. Therefore, the needle should enter the L3/4 or L4/5 disc space

The L3/4 disc space will be transected by the line that connects the iliac crests (as seen in Figure 2).

Figure 2: LP Landmarks (Picture from Bonadio, 2014)

Maximizing Success

As you are gathering your materials, you begin wondering what can be done to maximize the success of your procedure.

1.)Anesthesia

Topical (“EMLA”) vs local (1% lidocaine infiltration)

Use of local anesthetic associated with an increased odds ratio (OR = 2.2) for success (Baxter, 2006)

Other RCTs (Pinheiro et al, 1993; Nigrovic, 2007) found that local infiltration did not increase success, but statistically decreased the amount of struggling in infants.

Note: Despite not finding any differences in success rates between the two methods, it is important to note that local infiltration did not lead to decreased success (concern for a loss of landmarks, etc).

2.) Early stylet removal (“Cincinnati” Method)

In this method, the stylet is removed after puncturing the epidermis

Baxter et al found a trend towards increased success in residents employing this method, but this was not statistically significant (Baxter, 2006)

Nigrovic et al did find an association between leaving the stylet in and with the composite outcome of traumatic or unsuccessful lumbar puncture (Nigrovic, 2007)

Conclusion: Use an anesthetic (topical or local infiltrate) and consider removing the stylet early

Now that we know what we need, where we need to go, and what helps maximize success, how do we do the procedure?

Case: Zoe is a 10 day old ex- full term female, born to a G1P0 →1 presenting with feeding difficulties. Per her mother, she is exclusively breastfed and had initially had been doing “ok” but for the last couple days, has been more sleepy than usual and not feeding as well. She also notes that during this time, her eyes have become a bit more yellow.

On exam, you note an infant in no distress, but she sleeps comfortably through your exam. Jaundice is appreciated. Vitals are normal, but you note she has lost 12% of her birth weight. Her HEENT is notable for a sunken anterior fontanelle. Her exam is otherwise benign. Concerned for hyperbilirubinemia and dehydration, you order a complete metabolic panel, which, among other abnormalities, is significant for a serum sodium of 165 meq/L.

Why is her sodium so high?

Diagnosis: Severe neonatal hypernatremic dehydration

Pathophysiology

In this case, the most likely etiology is ineffective breastfeeding (also termed lactation failure), which is a rare, but increasing cause of hypernatremic dehydration (Mortiz et al, 2002)

In all humans (not just neonates), hypernatremia results from one of two mechanisms: inadequate access to free water and/or an inability to concentrate urine

Breastfeeding failure leads to inadequate fluid intake, but is also related to the higher concentration of sodium in breast milk (Morton, 1994)

How do patients present? (Moritz et al, 2005)

Over 70% of patients had > 10% weight loss

Signs at Presentation

% Of Infants (n=70)

Jaundice

81

Poor PO Intake

61

Decreased Urine Output

36

Fever

20

Table Adapted from Moritz et al, 2005

How common is this problem?

Neonatal hypernatremic dehydration is rare. A review of admissions to a major children’s hospital found that over 4 years, 1.9% of term and near term infants were admitted for hypernatremic dehydration (Mortiz et al., 2005)

Most commonly affects primiparous mothers

How should we treat?

The goal of treatment is to lower serum sodium in a slow and controlled fashion

Conventional teaching states that sodium should not be lowered faster than 0.5mEq/hr and in fact, recent studies suggest that correction faster than 0.5mEq/L/hr is independently associated with poor neurologic outcomes and seizures (Bolat et al, 2013)